Several issues have been identified with adding and moving columns and adding widgets to columns.
All known pagebuilder column issues have been resolved as of 9.1 SP1 CU 23. Please upgrade if you run into issues associated with columns when using pagebuilder. Some listed issues are below.
22401 - After you set a new numeric position for a PageBuilder column and resized it, the column was reset to the original position.
14397 - If you dropped a content block widget onto a PageBuilder page that included a Targeted Content widget, the content block did not drop into the correct position where you clicked. Instead, the content block went further down the column.